Scientific American Supplement, No. 508, September 26, 1885 eBook

When the reduction of aluminic oxide by carbon is
conducted without the addition of copper, a brittle
product is obtained that behaves in many respects
like pig iron as it comes from the blast furnace.
The same product is formed in considerable quantities,
even when copper is present, and frequently the copper
alloy is found embedded in it. Graphite is always
found associated with it, even when charcoal is the
reducing material, and analysis invariably shows a
very high percentage of metallic aluminum. This
extremely interesting substance is at present under
examination.

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THE COWLES ELECTRIC SMELTING PROCESS.

The use of electricity in the reduction of metals
from their ores is extending so rapidly, and the methods
of its generation and application have been so greatly
improved within a few years, that the possibility
of its becoming the chief agent in the metallurgy of
the future may now be admitted, even in cases where
the present cost of treatment is too high to be commercially
advantageous.

The refining of copper and the separation of copper,
gold, and silver by electrolysis have thus far attracted
the greatest amount of attention, but a commercial
success has also been achieved in the dry reduction
by electricity of some of the more valuable metals
by the Cowles Electric Smelting and Aluminum Company,
of Cleveland, Ohio. Both this method of manufacture
and the qualities of the products are so interesting
and important that it is with pleasure we call attention
to them as steps toward that large and cheap production
of aluminum that the abundance of its ores and the
importance of its physical properties have for several
years made the unattained goal of many skillful metallurgists.

The Messrs. Cowles have succeeded in greatly reducing
the market value of aluminum and its alloys, and thereby
vastly extending its uses, and they are now by far
the largest producers in the world of these important
products. As described in their patents, the Cowles
process consists essentially in the use for metallurgical
purposes of a body of granular material of high resistance
or low conductivity interposed within the circuit
in such a manner as to form a continuous and unbroken
part of the same, which granular body, by reason of
its resistance, is made incandescent, and generates
all the heat required. The ore or light material
to be reduced—­as, for example, the hydrated
oxide of aluminum, alum, chloride of sodium, oxide
of calcium, or sulphate of strontium—­is
usually mixed with the body of granular resistance
material, and is thus brought directly in contact with
the heat at the points of generation, at the same
time the heat is distributed through the mass of granular
material, being generated by the resistance of all
the granules, and is not localized at one point or
along a single line. The material best adapted